Production of leather



Patented Sept. 25, 1934 PATENT OFFICE 1,974,861 PRODUCTION OF LEATHER Giorgio Chiera, Torino, Italy, assignor to the firm J. R. Geigy A. G., Basel, Switzerland No Drawing Application April '27, 1934, Serial vNo. 722,815. In Germany May 11, 1933 2 Claims. (Cl. 149-2) As isweli knownv it isj'necessary to subject animal skins, before tanning, to a preparatory treatment for separatingthe epidermis and the under-skin. After liming and after removal of 5 the hair-bearing outer-'layer'the corium is left in a strongly swollen, plump and full condition, in whichit still enclqses residues of the liming agent.- 'If the skin istanned whilst it is in this swollen condition ityields only a poor leatheri ..gl3y bating or drenching, for example,

. with "a fermented infusion {of bran or dung'or even with pure enzymes; the swelling is reduced and the skinbecomesj'flaccid or fallen; whilst it is in this condition the residual impurities,

even those enclosedwithin the skin, can be removed easily by mechanical means.

At the same time the surface of theskin requires the favourable fcondition required for the tanning operation, this being recognized by 29 the slippery feel of the skin. The softness and.--,

suppleness of theleather obtained after tanning is dependent not only on the known specific action of the liming agent. but'also largely on the extent to; which the liming agent and the g5 impurities are removed. 7

This invention is based on the observation that a pre-treatr'nent of the skins, with a washing and emulsifying agent obtainable according to German Specification No. 506.338 from a pyro- 30 phosphate and glue, gelatin, proteins, saponin,

casein and so on, prior to. tanning, is remarkably suitable for the purpose of rendering the leather very soft and supple. If an animal hide which has been prepared for tanning in the usual manner is treated, before or after the hating or drenching operation, in a bath containing a washing and emulsifying preparation obtainable according to the aforesaid specification, there is obtained after tanning a leather which is much softer and more supple than that which is obtained with the aid of the hitherto usual hating processes. Thus a treatment in accordance with the invention may replace the hitherto usual bating processes. The duration of the treatment will vary according to the effect which is desired and according to the concentration of the bath.

The following example illustrates the invention, the parts being by weight:

Skins which have been prepared in the beamhouse in the usual manner by liming and bating are placed-in water having a temperature of 35-40 C., on the reel or in the drum and moved for 1-1 hours with the addition of 1-1 per cent of a mixture of 2 parts of neutralized sodium pyrophosphate and 1 part of casein. The skins are then washed and tanned in the usual manner. The proportion of the mixture of pyrophosphate and casein which is used depends upon the origin of the skins and must be greater the higher the content of the skins in fat.

Instead of casein, it may be possible to use in this example any natural, vegetable or animal albumen such as glue, gelatin, a protein, saponin and so on.

What I claim is:--

1. An improvement in the production of leather. consisting in subjecting the skin, in the course of the treatment preparatory to tanning, to a treatment with a solution of a washing and emulsifying agent obtainable from a pyrophosphate and any natural, vegetable or animal albumen.

2. An improvement in the production of leather, consisting in subjecting the skin, in the course of the treatment preparatory to tanning, to a treatment with a solution of a washing and emulsifying agent obtainable from sodium pyrophosphate and casein.

GIORGIO CHIERA. 

